Along with Stanley N. Cohen and Paul Berg he discovered a method to coax bacteria into producing foreign proteins, thereby jump starting the field of genetic engineering. By 1969, he performed studies on a couple of restriction enzymes of the E.coli bacterium with especially useful properties. He is recipient of the 1990 National Medal of Science, co-recipient of the 1996 Lemelson–MIT Prize, and a co-founder of Genentech.